Software as a service (SaaS) is a software distribution model in which a service provider or vendor hosts applications for its customers. The hosted applications can be accessed by the customers over the Internet. In SaaS models, applications are centrally hosted and managed by the service provider. The customers may obtain licences which define their access rights, privileges, and usage parameters while accessing the hosted applications.
SaaS based platforms may use a multi-instance architecture or a multitenant architecture. In the multi-instance architecture, multiple customers are served by a separate instance of an application and an operating system running on a separate virtual machine implemented on a common hardware infrastructure, such as a server. In the multitenant architecture, a single instance of an application runs on the server and serves multiple customers, and each customer has a separate database to enable data isolation between the customers.